IICRC S520 Mold Containment & Negative Air Scrubber (WTR NAFAN) Photo Audit: Manometer & Zipper Chamber Proof
Xactimate Codes: WTR CONT, WTR NAFAN, HMR HEPA, HMR BARR | Standard: ANSI/IICRC S520 §10.4 & §12.2 | Protected: +$2,940 per mold remediation job
Technical Answer Summary (ANSI/IICRC S520 §10.4 & §12.2)
Under ANSI/IICRC S520 §10.4, Condition 3 mold remediation requires isolating the work zone with 6-mil polyethylene sheeting (WTR CONT / HMR BARR) and exhausting HEPA-filtered air outside the containment via an Air Filtration Device (WTR NAFAN) to maintain a continuous negative pressure differential of at least -0.02 inches of water column (-5 Pascals). Insurance adjusters regularly cut WTR NAFAN to a "recirculating air scrubber" rate or disallow containment assembly charges if the contractor only photographs an unplugged air scrubber sitting in an open room. Documenting the sealed 6-mil poly barrier, heavy-duty peel-and-stick zipper entry, exhaust lay-flat ducting, and a digital manometer displaying -0.025 in. w.c. guarantees full payment.
Adjuster Denial Trap: Adjusters denying negative air machine days (WTR NAFAN) and containment SF (WTR CONT) when photos fail to show exhausted ducting creating negative pressure (inward-bowed poly + digital manometer reading >= -0.02" w.c.).
3-Column Xactimate Denial Trigger vs. Field Photo Evidence Matrix
| Adjuster Denial Reason / Scrub Trigger | Required Field Photo & Meter Evidence (IICRC Standard) | Copy-Paste Xactimate F9 Note Justification |
|---|---|---|
| Adjuster disallows WTR NAFAN claiming unit was used only as an open-room air cleaner | Photo of AFD connected to 10-inch lay-flat exhaust ducting passing through a sealed port in the 6-mil poly containment wall + manometer reading -0.02" w.c. | HEPA Air Filtration Device (WTR NAFAN) was ducted through the containment barrier to establish continuous negative pressure (-0.024 in. w.c., verified via attached digital manometer photo) per ANSI/IICRC S520 §10.4. |
| Carrier cuts WTR CONT square footage by counting only the doorway opening | 4-corner wide photos + tape measure showing full floor-to-ceiling 6-mil poly walls, critical barrier seals over HVAC registers, and entry airlock chamber | Full source containment + decontamination airlock required 440 SF of 6-mil flame-retardant poly sheeting (WTR CONT) taped to ceiling/floor perimeters and HVAC supply/return vents. |
| Reviewer strikes HMR HEPA (HEPA vacuuming of framing and surfaces) | Photo of technician operating a serialized HEPA vacuum brush attachment on wire-brushed/sanded wall studs prior to antimicrobial wipe | Per IICRC S520 §12.2, physical removal of fungal hyphae via wire brushing/sanding followed by double HEPA vacuuming (HMR HEPA) is mandatory before post-remediation verification (PRV) clearance. |
Copy-Paste Xactimate F9 Note Justification
F9 NOTE (WTR CONT / WTR NAFAN / HMR HEPA): Remediation performed in strict compliance with ANSI/IICRC S520 (3rd Ed.) §10.4 and §12.2 for Condition 3 microbial growth. Work area was isolated using 6-mil polyethylene containment barriers (WTR CONT) with sealed HVAC critical barriers and a double-zipper decontamination airlock. Continuous negative pressure of -0.024 in. w.c. (-6.0 Pa) and >4 ACH were maintained using a ducted HEPA Air Filtration Device (WTR NAFAN) until third-party Industrial Hygienist PRV air clearance was achieved.
Mandatory On-Site Field Photo Checklist
- Hard Gate #1: Pre-demolition close-up of visible Condition 3 fungal growth with scale ruler
- Hard Gate #2: Full 6-mil poly containment barrier showing inward belly from negative pressure
- Hard Gate #3: Digital differential pressure manometer reading at least -0.02 in. w.c. (-5 Pa)
- Hard Gate #4: HEPA vacuuming & wire-brushing of exposed framing prior to PRV clearance test
Frequently Asked Questions
What negative pressure reading is required by IICRC S520 for mold containment?
Industry standard under ANSI/IICRC S520 and EPA mold guidelines is a minimum pressure differential of -0.02 inches of water column (-5 Pascals) with at least 4 to 6 Air Changes Per Hour (ACH) exhausted through a certified HEPA filter.
Can I bill WTR NAFAN during the waiting period for Industrial Hygienist Post-Remediation Verification (PRV) lab results?
Yes. Under IICRC S520 §12.2.11, containment barriers and negative air control must remain erected until passing PRV clearance results are received so that if additional cleaning is needed, spores do not migrate into unaffected rooms.